In-orbit checkout feedback from the infrared imaging radiometer for the CALIPSO mission

The Calipso mission aims to provide the geographic location, altitude and optical properties of cloud layers and aerosols to help scientists understand how they shape climate processes. The payload is composed of three instruments, a two-wavelength (532 nm and 1064 nm) polarization-sensitive backscatter Lidar, a Wide Field visible Camera (WFC) and the Imaging Infrared Radiometer (IIR). The satellite was launched on the 28th of April 2006. The IIR is an infrared three channel broadband radiometer which uses an uncooled infrared microbolometer detector. The use of this microbolometer technology allows the design of compact and low-consumption infrared instruments while providing acceptable radiometric performances. The IIR provides calibrated infrared radiances at three wavelengths (B1 : 8.2-9.1 μm - B2 : 10.3-10.9μm - B3 : 11.55- 12.55 μm), which will be combined with daytime and nighttime lidar measurements to retrieve radiative and microphysical parameters of clouds. This paper reminds of the Calipso mission goal, then describes the IIR instrument architecture and highlights its main features. It presents the performances achieved in flight by analysing the data provided by the IIR during checkout phase.